Orthogonal frequency division multiplexing (OFDM) is a multi-carrier transmission technique in which a user transmits on many orthogonal frequencies (or subcarriers or tones). The orthogonal subcarriers (or tones) are individually modulated and separated in frequency such that they do not interfere with one another. This provides high spectral efficiency and resistance to multipath effects. An orthogonal frequency division multiple access (OFDMA) system allows some subcarriers to be assigned to different users, rather than to a single user.
The performance of an OFDM network may be improved by selecting modulation and coding rates at a base station based on channel quality feedback from the receiving stations (e.g., subscriber stations) in the wireless network. However, suboptimal selections of coding rate and modulation result in link inefficiency and an eventual degradation in the wireless system performance. Therefore, there is a need in the art for an OFDM network that is able to provide coding and modulation with increased link efficiency under various channel conditions, thereby improving network performance.